Plain English Summary

Background and study aims There is a lot of epidemiological evidence to suggest that eating more wholegrain foods, for example millet, brown rice and oatmeal, reduces the risk of developing several diseases including cardiovascular disease (e.g. heart disease), type 2 diabetes and some cancers. This had led to a dietary recommendation of eating 48g of whole grains being suggested in the United States and 75g per day being recommended in Denmark. In other European countries, there is no specific dietary recommendation, but it is recognized that whole grains should be an important part of a healthy diet. Although the epidemiological evidence is strong, results from studies that compare different diets (intervention studies) have been more varied. Some studies have shown a whole grain diet as beneficial, others have not. This means that, at the moment, no definite conclusions regarding the protective role of whole grains against disease can be made. In particular, the amount of whole grains that should be eaten in order to get any health benefits is not proven, with estimates ranging from as little as one to more than three servings per day. We have already carried out two large intervention studies looking at including whole grains in the diet. One study, the WHOLEheart study, showed no beneficial effects of eating whole grains, but the amount of whole grain being eaten was not well controlled and the participants ate mixtures of grains (wheat, rice and rye). In our second study, the GrainMark study, the amount of whole grain being eaten was much better controlled and the participants ate only wholegrain wheat or wholegrain rye foods. This time, there was significant improvements in cholesterol levels and blood pressure, but, as the study did not include a control group (a group of participants that did not eat a whole grain diet) we cannot say for sure that these improvements were due to the whole grains. Here, we are doing a third whole grain intervention study, building on our previous experiences, using a gold standard experimental design developed to reduce the variability of the whole grains being eaten, to ensure a substantial increase in the amount of whole grains being eaten compared to the average in the UK and to improve statistical robustness.

Who can participate? Generally healthy nonsmoking men and women aged between 40-70, with a BMI between 25 and 35 kg/m2, slightly increased blood pressure and slightly increased cholesterol levels.

What does the study involve? Participants are asked not to eat any wholegrain foods for the four weeks leading up to the start of the study. After this washout period they are randomly allocated into one of two groups. Those in group 1 are given a wholegrain bread and breakfast cereal to eat in place of that they normally eat and asked to eat 4 servings per day if a woman and 6 servings a day if a man for 4 weeks. One serving is equal to one slice of bread or half a bowl of cereal. Those participants in group 2 are given similar instructions but are given bread and breakfast cereal made from refined wheat. After the 4 weeks, all participants are asked to not eat wholegrain foods for a further 4 weeks before swapping diets. This means that those in group 1 now eat the refined bread and cereal and group 2 the wholegrain foods for the last 4 weeks of the study. Urine and blood samples from each participant are taken at 4-weekly intervals throughout the trial. On the evening before samples are collected, each participant is asked to eat a supplied standard meal and then fast from 9pm. Height, weight, waist, hip, body fat and blood pressure measurements are also taken throughout the trial and the participant asked to fill in questionnaires.

What are the possible benefits and risks of participating?If any abnormalities of significance are discovered while measuring their cholesterol, blood pressure or blood glucose levels, we will tell the participant and their GP so that appropriate steps can be made. Taking blood samples can cause minor discomfort and bruising. If a new diagnosis of high blood pressure is made, however, this could affect a persons future life or private medical insurance.

Where is the study run from? The Clinical Research Facility, Royal Victoria Infirmary (Newcastle)

When is the study starting and how long is it expected to run for? June 2014 to June 2015

Contact information

Type

Primary contact

ORCID ID

Contact details

Additional identifiers

EudraCT number

ClinicalTrials.gov number

Protocol/serial number

013.WG wheat and heart health.UK.2013

Study information

Scientific title

Wholegrain wheat and cardiovascular health

Acronym

Study hypothesis

The proposed research is a dietary intervention study to investigate the health benefits of increased consumption of wholegrain wheat. There is strong evidence from observational (epidemiological) studies to suggest that consumption of wholegrain foods is beneficial in reducing the risk of heart disease, although evidence from intervention studies is more mixed. The aim of this study is to investigate the impact of consuming whole and refined wheat products on markers of cardiovascular disease. The objective is to carry out a controlled 16 week dietary intervention in crossover design to investigate the effects of consuming whole and refined grain wheat products in equal amounts on cardiovascular disease risk factors, in particular LDL cholesterol concentration. The purpose is to provide evidence to support public health messages to increase consumption of wholegrain foods.

Ethics approval

London city and east NHS research committee, 20/12/2013, ref. 13/LO/1883

Study design

Randomised crossover dietary intervention.

Primary study design

Interventional

Secondary study design

Randomised controlled trial

Trial setting

Other

Trial type

Prevention

Patient information sheet

Condition

Cardiovascular health

Intervention

Participants will first be asked to avoid wholegrain foods for 4 weeks. They will then be randomly allocated into one of two groups.1. Participants will be provided with wholegrain bread and cereals to consume for 4 weeks.2. Participants will be provided refined grain bread and cereals to consume for 4 weeks.They will then be a "wash out" period, where participants are asked to avoid whole grain foods for another 4 weeks. They then "swap over" to the other group - so that group 1 now eats the refined grain foods and group 2, the wholegrain foods, for a further 4 weeks.

Participant type

Patient

Age group

Adult

Gender

Both

Target number of participants

82

Participant exclusion criteria

1. Known allergy to study (wheatbased) foods.2. History of metabolic disease (i.e.diabetes, cardiovascular disease) relevant for drug treatment.3. Chronic renal insufficiency.4. Local or general treatment (i.e. prescription medications, overthecounter medications, dietary supplements or herbal supplements) known to interfere with the evaluation of the studied parameters.5. Subject having had a general anaesthesia in the month preceding inclusion, or gastrointestinal surgery.6. Pregnant or breastfeeding subject.7. Use of laxatives.8. Known allergies to cereals.9. Dislike of provided study foods.